Unit Charge Research Articles

A behavioral method to estimate charge integration efficiency in cochlear implant users

BackgroundIn cochlear implants, pulse amplitude (PA) or pulse phase duration (PPD) can be used to increase loudness. Loudness grows more slowly with increasing PPD, resulting in a larger dynamic range (DR), possibly reflecting “leaky” charge integration associated with neural degeneration due to hearing loss. Here, we propose a method to estimate charge integration efficiency for CI users. New methodThe DR was measured with increasing PA or PPD, relative to a common threshold anchor with a short PPD (25μs/ph); DRs were converted to the common unit of charge (nC). Charge integration efficiency was calculated as the dB difference in DR with increasing PPD or PA. Loudness growth functions were also compared as PA or PPD was increased relative to the common threshold. ResultsTen CI ears were tested; all participants were adult users of Cochlear© devices. DR was significantly larger when PPD was increased, requiring (on average) 70 % more charge than when PA was increased. A significant correlation (p = 0.007) was observed between duration of deafness and charge integration efficiency, largely driven by a participant with long auditory deprivation in both ears. Loudness growth was slower when PPD was increased, consistent with previous studies.Comparison to Existing Methods. The present method offers a quick behavioral test with which to measure charge integration efficiency, which may be a useful measure of neural health. DiscussionCharge integration efficiency may be used to probe neural health independent of absolute detection thresholds, which mostly reflect the proximity of electrodes to neural populations.

Optimization of Electric Vehicle Charging for Battery Maintenance and Degradation Management

Battery management for plug-in electric vehicles (PEVs) has attracted extensive research attention, with most existing studies focusing on PEV operating conditions. However, battery maintenance during idling remains largely unexplored, under which electrochemical side reactions can cause battery degradation. The degradation rate depends on battery states, e.g., state of charge (SOC) and temperature. Considering that PEV idling accounts for the majority of the time, the accumulated degradation could have a major impact on battery and vehicle lifetime. In this article, battery maintenance during extended idling periods is investigated by utilizing a commonly available infrastructure, i.e., the charging unit. An optimal charging profile is designed to maintain the battery states under desirable conditions to minimize degradation over the idling period while still satisfying the charging energy requirement. Optimal charging profiles are obtained under different ambient temperatures and stages of battery life, showing different features due to respective dominating degradation mechanisms. Compared with the optimal charging profile, constant-current (CC) charging could result in up to 51.6% higher capacity loss, and that of (fast) CC-constant-voltage charging could be up to 12.3 times higher under circumstances over a 12-h overnight idling period. Integration/accommodation of user and grid demand is also addressed by augmenting the optimization framework.

Gradient supercritical fluid chromatography coupled to mass spectrometry with a gradient flow of make-up solvent for enantioseparation of cathinones

In the past two decades, supercritical fluid chromatography has evolved from a niche application to a comprehensive technology and a fully-fledged alternative to conventional high-performance liquid chromatography.In this study, we have focused on chiral separation of synthetic cathinones in gradient supercritical fluid chromatography coupled to mass spectrometry using an inverse gradient of a make-up solvent. Synthetic cathinones possess an amphetamine-like effect and, therefore, are frequently being offered on the Internet as a replacement for illicit drugs. Cathinones are chiral compounds, however, they are usually marketed and used as racemic mixtures. Since the effect of individual enantiomers can significantly vary, there is a need for the development of enantioseparation methods enabling to study the biological effects of individual enantiomers. Since cathinones are basic molecules, they are easily protonated (positively charged) under weakly acidic mobile phase conditions, which is a typical feature of supercritical mobile phases with an alcohol as an organic modifier. The positively charged species represent ideal analytes for ion exchangers, such as chiral zwitterion ion exchangers Chiralpak ZWIX (+) and Chiralpak ZWIX (−), which possess a positively and negatively charged unit in the molecular structure of the selectors. The presence of the positive charge in the selector's structure, functioning as a counter-ion for the positively charged analytes, significantly reduces the required amount of a buffer, which is plausible for hyphenation of such a separation system with mass spectrometry. For mass spectrometry hyphenated to supercritical fluid chromatography, the use of a make-up solvent is required to avoid analyte precipitation when using a low concentration of an organic co-solvent (modifier) in the super-/subcritical mobile phase. Hereby, we introduce a unique approach, which is based on the gradient introduction of the make-up to the post-column effluent. Using this approach, it is possible to keep constant the overall amount of the organic solvent (modifier and make-up) introduced into the mass spectrometer when using a gradient of the organic modifier. We show that the developed gradient elution method facilitates the chiral separation of all employed analytes, while the mobile-phase gradient compensation by the inverse make-up gradient enables their detection with high signal intensities.

Behavior of ultrafine particles in electro-hydrodynamic flow induced by corona discharge

Ultrafine particle behavior in electro-hydrodynamic (EHD) flow induced by corona discharge is studied experimentally and numerically. The EHD flow serves as a primary particle aspiration/sampling mechanism, the collector does not require any additional flow generation. Multiphysics numerical model couples the ion transport equation and the Navier-Stokes equations (NSE) to solve for the spatiotemporal distribution of electric field, charge density, and flow field, the results are compared with experimental velocity profiles at the exit. The computed velocity and flow rate data are in good agreement with the experimental data; the maximum velocity is located at the axis and ranges from 1 m/s to 4 m/s as a function of corona voltage. Experimentally evaluated particle transmission trends for ambient and NaCl nanoparticles particles in the 20 nm–150 nm range are in good agreement with the theoretical models. However, for particles in the 10 nm–20 nm size range, the transmission is lower due to the increased particle charging resulted from their exposure to the high-intensity electric field and high charge density in the EHD driven flow. These conditions yield a high probability of particles below 20 nm to acquire and hold a unit charge. The transmission is lower for smaller particle (10 nm) due to their high charge to mass ratio, and it increases as the single-charged particles grow in mass up to 20 nm, resulting in their lower electrical mobility. For particles larger than 20 nm, the electrical mobility increases again as they can acquire multiple charges. The results shed insight into interaction of nanoparticle and ions in high electrical field environment, that occur in primary EHD driven flows and in the secondary flows generated by corona discharge.

Nuclei charge measurement by the Alpha Magnetic Spectrometer silicon tracker

The Alpha Magnetic Spectrometer (AMS) is a high energy particle detector aboard the International Space Station. AMS precisely measures the fluxes of all cosmic-ray nuclei with charge from Z=1 to Z=28 and beyond. The AMS silicon tracker measures energy deposition of charged particles traversing over nine-layer silicon sensors, from L1 to L9. In this paper, the details of the AMS silicon tracker charge measurement method are presented. The obtained charge resolution of the AMS inner tracker (L2 to L8 combined) is 0.1 charge units for carbon, 0.15 charge units for silicon, and 0.3 charge units for iron nuclei.

Numerical study of a Phase Change Material (PCM) embedded solar thermal energy operated cool store: A feasibility study

Solar energy has proved to be an ideal alternative for fossil fuels, however, due to its intermittency in availability, systems operated by solar energy face serious limitations. In this study, a simplified dynamic model is developed to investigate the behavior of a PCM-embedded cool store. The main application of this type of cool store is to be operated with a solar thermal refrigeration system to compensate for the intermittency in energy availability. 8640 kg of crops (potatoes) is considered to be stored inside the cool store along with PCM cold thermal energy storage units. 9 h of active and 15 h of inactive period are considered for 24 h operation of the refrigeration system based on the solar energy availability data. During the active period, PCM units charge, and during the inactive period, they discharge and regulate the temperature inside the cool store. It was revealed that by choosing the right properties, PCM can keep the temperature of the crops in the desired range during the inactive period of the refrigeration system. Also, it was observed that the amount of PCM used and the phase change temperature of the PCM has a significant impact on the performance of the system. The lowest temperature obtained for the crops during the inactive period of the refrigeration system is for the case with PCM to crops amount ratio of 0.026 with PCM phase change temperature of 9 °C in which the discharge process finishes around the end of the inactive period of the refrigeration.

Highly Branched Waxy Potato Starch-Based Polyelectrolyte: Controlled Synthesis and the Influence of Chain Composition on Solution Rheology

In the present work, a series of highly branched random copolymers of acrylamide (AM), sodium 2-acrylamido-2-methyl-1-propanesulfonate (SAMPS), and N-isopropylacrylamide (NIPAM) were prepared by using water-soluble waxy potato starch-based macroinitiator via aqueous Cu0-mediated living radical polymerization (25 °C). The AM/SAMPS/NIPAM ratio was varied to investigate the influence of chain composition on the aqueous rheological properties of the prepared copolymers. Rheological results indicated an optimum SAMPS intake (25 mol %) for the balanced performance of viscosity and salt resistance in saline water. The intake of NIPAM units (e.g., 25 mol %), contrary to what was expected, undermines the thickening ability of the copolymers in saline water because of hydrophobic association. In high salinity solution, thermo-thickening behavior can be observed at low shear rates (γ ≤ 3 s–1) because of the screening effect of salt on the negatively charged SAMPS units. At the high shear rate, the thermo-thickening behavior disappears because of the disruption of the NIPAM aggregates. These results pave the way toward the use of the prepared polymers as rheology modifiers in a variety of possible formulations for different applications, in particular in enhanced oil recovery.

Power Charging Unit using Rotary Leverage System

Power Charging Unit using Rotary Leverage System

The Mechanism of Doping and the Features of Phase Diagrams of HTSC Cuprates and Ferropnictides

We propose a generalized model of electronic structure modification in HTSC cuprates and ferropnictides under doping. In this model the role of doping consists in only a local change in the electronic structures of the parent phases of cuprates and ferropnictides due to the formation of trion complexes comprising a doped carrier localized in unit cell and charge transfer (CT) excitons around it. These CT excitons emerge in CuO4 or AsFe4 plaquettes in the CuO2 or FeAs basal planes (CT plaquettes) under the influence of doped carrier, restricting its itinerancy. As the dopant concentration is increased, CT plaquettes combine into clusters of the so called CT phase. It is this CT phase that is related in the model to the HTSC phase. In support of this assumption, we determined the ranges of dopant concentrations conforming to the existence of percolation clusters of the CT phase; these ranges were shown to coincide with the positions of the superconducting domes on the phase diagrams of these compounds. The model also perfectly describes subtle features of the phase diagrams of various cuprates and ferropnictides including the 1/8 anomaly, narrow peaks in the dependences of the London penetration depth on the concentration of the dopant, and other specific features. The mechanism of the generation of free carriers in the CT phase, provided by intrinsic self-doping, was considered. The mechanism is not directly related to external doping, but is due to the interaction of band electrons with so called Heitler-London (HL) centres inherently existing in the percolation cluster of CT phase and representing pairs of adjacent CuO4 or AsFe4 CT plaquettes in the CuO2 or FeAs basal planes. Material in CT phase was shown to represent a medium, in which the mechanism of excitonic superconductivity, specified by the interaction of band electrons with HL centres, can be realized.

Inkjet jettability and physical characterization of water–ethanol solutions of low molecular weight sodium polyacrylate and poly-diallyl dimethyl ammonium chloride (polyDADMAC)

Polyelectrolytes are water-soluble polymers having repeat units carrying electrolyte groups. As polyionic molecules having like charge units, they are self-repelling with a rod-like conformation in solution. Inkjet applications of polyelectrolytes include particle dispersing, surface modification, and multilayer structures. This work investigates the physical properties of low molecular weight sodium polyacrylate (NaPA) and poly-diallyl dimethyl ammonium chloride (polyDADMAC) polyelectrolyte solutions in the water–ethanol mixture in relation to their behavior in inkjet deposition. In rotational rheometry measurements, the solutions are found to behave in a Newtonian fashion once the effects of experimental artifacts are taken into account. The range of NaPA concentrations that could be studied was limited to 1 wt./wt. % by the poor solubility of NaPA in the presence of ethanol, and at these concentrations, the addition of NaPA to the solvent did not have a significant effect on the jetting behavior. PolyDADMAC had good solubility, and concentrations up to 10 wt./wt. % were studied and jetted successfully. While an increase in polyelectrolyte concentration resulted in a slow increase in ink viscosity, this was not found to have a significant effect on the required jetting voltage or maximum stable jetting frequency, though drop detachment and satellite droplet formation times were found to increase. As a practical limitation of polyDADMAC inks, solvent evaporation was found to lead to idle nozzles becoming non-jetting, with the allowed idle time decreasing rapidly as ink polyDADMAC concentration increased. This non-jetting behavior is likely due to residence time at the nozzle exit leading to the local surface tension and/or viscosity increase, differing from the bulk ink properties.

Positively and Negatively Charged Porphyrin Metal Complexes That Form Ion-Pairing Assemblies

An ordered arrangement of π-electronic species is crucial for the fabrication of functional organic materials such as organic electronic devices including field-effect transistors, light-emitting diodes, and photovoltaic cells. Synergetic uses of electrostatic interactions and other noncovalent interactions, including π–π stacking, is very important for the alignment of π-electronic charged species (cations and anions) and the formation of dimension-controlled assemblies including fiber and sheet solid materials, supramolecular gels, and liquid crystals.[1,2] An advantage of using electrostatic interactions is the formation of various ion-pairing materials by combining constituent π-electronic ions: for example, ten kinds of cations and ten kinds of anions are mixed to ideally provide one hundred kinds of ion pairs. Furthermore, assembling modes can be modulated by constituent ions as well as by the environment, thus exhibiting particular properties according to the arrangement of charged building units even in an ion pair. In this study, porphyrin–AuIII complexes were found to act as π-electronic cations which can combine with various counteranions, including π-electronic anions such as negatively charged porphyrin metal complexes. In the solid-state and soft materials, the formation of assemblies with contributions of charge-by-charge and charge-segregated assemblies, whose ionic components were highly organized by π–π stacking and electrostatic interactions, depended on the geometries and electronic states of constituent ionic species.[3,4]

PCN205 ATEZOLIZUMAB PAY FOR PERFORMANCE MODEL, FOR THE TREATMENT OF PRIVATE PAYER CHILEAN PATIENTS WITH THE DIAGNOSIS OF NON-SMALL CELL LUNG CANCER (NSCLC) & METASTATIC UROTHERIAL CANCER (MUC)

Design a performance-based reimbursement scheme that could benefit the patient population of NSCLC and mUC to estimate the impact on the private payer access for this treatment in Chile. Based on progression-free survival of pivotal clinical trials (OAK & IMvigor211 studies) we developed a model using the probabilistic analysis to maximize patients’ and payers’ benefits within the riskier period of disease progression. Inclusion and exclusion criteria were defined as minimum requirements to start the program. For 2L NSCLC and mUC, the risk is shared between Roche and payers in a 50% scheme, since 50% of patients would relapse within the first 3 months of treatment (first 4 cycles of treatment), according to clinical trials. For the following cycles (5th onwards) to benefit long-term responders, after three cycles of treatment, a free of charge unit will be provided. Performance-based funding is not a uniform intervention, but rather a range of approaches. Its effects depend on the interaction of several variables, including the design of the intervention and characteristics of the healthcare system. In this case, the financial benefit is for the whole healthcare system, because it reduces the risk during the first 4th cycle of treatment and also benefits long-term responders. This model will be expanded to the Chilean public payer in the future.

Synthesis of a Counteranion-Stabilized Bis(silylium) Ion.

The preparation of a molecule with two alkyl‐tethered silylium‐ion sites from the corresponding bis(hydrosilanes) by two‐fold hydride abstraction is reported. The length of the conformationally flexible alkyl bridge is crucial as otherwise the hydride abstraction stops at the stage of a cyclic bissilylated hydronium ion. With an ethylene tether, the open form of the hydronium‐ion intermediate is energetically accessible and engages in another hydride abstraction. The resulting bis(silylium) ion has been NMR spectroscopically and structurally characterized. Related systems based on rigid naphthalen‐n,m‐diyl platforms can only be converted into the dications when the positively charged silylium‐ion units are remote from each other (1,8 versus 1,5 and 2,6).

Surface charge theorem and topological constraints for edge states: Analytical study of one-dimensional nearest-neighbor tight-binding models

For a wide class of noninteracting tight-binding models in one dimension we present an analytical solution for all scattering and edge states on a half-infinite system. Without assuming any symmetry constraints we consider models with nearest-neighbor hoppings and one orbital per site but arbitrary size of the unit cell and generic modulations of on-site potentials and hoppings. The solutions are parametrized by determinants which can be calculated from recursion relations. This representation allows for an elegant analytic continuation to complex quasimomentum consistent with previous treatments for continuum models. Two important analytical results are obtained: (1) An explicit proof of the surface charge theorem is presented including a unique relationship between the boundary charge $Q_B^{(\alpha)}$ of a single band $\alpha$ and the bulk polarization in terms of the Zak-Berry phase with no unknown integer left. This establishes a precise form of a bulk-boundary correspondence relating the {\it boundary charge of a single band} to bulk properties. (2) We derive a topological constraint for the phase-dependence of the edge state energies, where the phase variable describes a continuous shift of the lattice towards the boundary. The topological constraint is shown to be equivalent to the quantization of a topological index $I=\Delta Q_B-\bar{\rho}\in \{-1,0\}$ introduced in an accompanying letter [arXiv:1911.06890]. Here $\Delta Q_B$ is the change of the boundary charge $Q_B$ for a given chemical potential in the insulating regime when the lattice is shifted by one site towards the boundary, and $\bar{\rho}$ is the average charge per site (both in units of the elementary charge $e=1$). This establishes an interesting link between universal properties of the boundary charge and edge state physics discussed within the field of topological insulators.

Economic model for an electric vehicle charging station with v ehicle‐to‐grid functionality

Energy consumption is increasing in parallel with the population and technological advancements. Albeit the energy efficiency efforts, industrial consumption, and transportation have quite important roles in this increase. The electric vehicles (EVs) are expected to constitute a positive solution to mitigate energy use in transportation. Increasing penetration of EVs into public transport provides new opportunities both for environmental sustainability and transportation infrastructure. To project the potential operator revenue, we set up a hybrid model (solar and storage), which optimizes scheduling for the EV charging unit and evaluates environmental and economic benefits. Different operational scenarios of PV-assisted charging stations will be simulated and solved with Rule-based decision making. Since regulations have an important role in building the optimization model, scenarios are created considering different European regulations. Uncertainties depending on the traffic jam (arrival-departure times), technological differences of the charging stations are encountered in the model. The results are compared among three different scenarios. Net present value of the system changes for different scenarios and electricity sale price is one of the main factors. This value tends to increase after an annual electricity sale price increase rate of 11%. Novelty statement In this study, the effect of different economic parameters on an electric vehicle charging station were analyzed. A system with electric vehicles, solar panel support, and external battery was mathematically modeled and a case study was done.

A two-layer dynamic voltage regulation strategy for DC distribution networks with distributed energy storages

In this article, a two-layer bus voltage regulation strategy with distributed energy storages (DESs), is proposed for dc distribution networks. The developed droop principle based on the power coupling characteristics of ac/dc interface is derived as the basis of the primary control. Besides, the state of charge (SoC) of DES unit is considered inherently in the primary regulation, which can effectively contribute to the long-term performance and life span of DES unit. Then, the cost characteristics of DES device and its connecting converter are analyzed in detail, and the secondary voltage regulation is accordingly designed based on the developed dynamic equal incremental cost principle. The proposed two-layer voltage regulation can achieve the economic power dispatch during the multi-bus voltage regulation without deteriorating the voltage quality, which can obtain a trade-off between the voltage performance improvement and the DESs economic operating. The performance of the proposed control strategy is validated with different operating conditions in the case studies.

Direct Determination of a Bare Neutron Counter Yield Function

AbstractGround‐based neutron counters are a standard tool for detecting atmospheric showers from GeV range primary cosmic rays of either solar or galactic origin. Bare neutron counters, a type of lead‐free neutron monitor, function much like standard neutron monitors but have different yield functions primarily because they are more sensitive to neutrons of lower energy. When operated together with standard monitors, the different yield functions allow estimates to be made of the energy spectrum of galactic or solar particles. In 2010 a new array of 12 bare neutron detectors was installed at the South Pole to operate together with the neutron monitor there. Prior to installation, two of the detectors were operated on a ship that traveled from Sweden to Antarctica and back from November 2009 to April 2010. The purpose of this latitude survey was to use Earth's magnetic field as a spectrometer, blocking cosmic rays below the local cutoff rigidity (momentum per unit charge), from which we determined the response function versus rigidity of these bare counters. By comparing that measured response function to direct measurements of the cosmic ray spectrum taken by the PAMELA spacecraft, we were able to make a direct determination of the yield function for these detectors.

Molecular-Dynamics Simulation of Rearrangements in the Conformational Structure of Polyampholytic Macromolecules on the Surface of a Polarized Metal Nanoparticle

Molecular dynamics has been employed to study rearrangements in the conformational structure of polyampholytic macrochains with different distributions of charged units in the electric field of a polarized metal nanoparticle. The angular and radial distributions have been calculated for the average densities of polypeptide atoms. The radial distributions of the average density of polypeptide atoms have been obtained in the vicinities of the positively and negatively charged poles of the nanoparticle, as well as in its equatorial region. An analytical model has been proposed for conformational rearrangements of an adsorbed macrochain in the field of the polarized nanoparticle. The formation a nonuniform distribution of the density of polypeptide atoms has been analyzed as depending on the angle between the directions of the dipole moment vector and the vector of the normal to the nanoparticle surface. Swelling of the macromolecular “fringe” has been observed with the predominant protrusion of loops in the direction of the polarization axis.

Structural, electronic, and vibrational properties of choline halides

X-ray angular diffraction, IR absorption spectroscopy, density functional theory with gradient-corrected PBE and hybrid B3LYP functionals with D3(BJ) dispersion correction in the basis of localized orbitals were used to study the structural, electronic, and vibrational properties of synthesized сholine halides (ChCl, ChBr and ChI). Under normal conditions, choline chloride and bromide have a rhombic structure, while iodide has a monoclinic one. The halogen atom has 12 hydrogen atoms in its nearest environment with the shortest distance O–H⋯Cl(I) 2.156 (2.486) Å (the PBE + D3 method). The halogen (Hal) atom charge is −0.8, oxygen is −0.5, and hydrogen is +0.3 units of the electron charge (the Mulliken scheme). The interaction energy per one formula unit is −80 kcal/mol. The p-states of halogen with oxygen form the upper valence band, s-hydrogen form the conduction band, so that the energy gap decreases from chloride to iodide from 5.87 to 5.35 eV. The most intense peaks of IR spectra in ChCl, ChBr, ChI at 3255, 3256, 3331 cm-1 refer to O–H stretching vibrations, 1092, 1080 cm-1 – to C–OH stretching, and 620 cm−1 – to O–H bending vibrations, i.e. directly to the O–H⋯Cl(I) bond. The calculated frequency values fit well into the linear dependence on the ionic radius of halogen.

Self-force subtraction in particle in cell simulations

A method is presented to remove the numerical self-force that appears in particle-in-cell (PIC) simulations in computational domains discretized with general meshes and boundary conditions. The self-force is a non-physical force that a particle exerts on itself as a result of the discretization of charge density on a computational grid, and the interpolation of electric fields back to particle positions. With a uniform grid and periodic boundary conditions, Hockney and Eastwood (1988) demonstrated that this spurious force can be suppressed to machine accuracy if consistent interpolations of particle charges to grid points, and electric field back to particle positions are used. In non uniform unstructured meshes with multiply connected domains, or more general boundary conditions however, the self-force is unavoidable in the standard PIC approach, which can be a concern in some simulations. In this paper a straightforward and efficient method is presented to suppress the self-force for unstructured meshes and open boundary conditions in electrostatic codes as used, for example, to simulate spacecraft-environment interaction. The method consists of precomputing an array of self-forces associated with unit charges at each mesh vertex of the computational grid, which can then be used to interpolate the self-force at any particle position. The computed self-force can then be subtracted from the force computed in the standard PIC approach thus enabling particle trajectory integrations that are free from this unphysical force. The method is illustrated with simulation results using an unstructured tetrahedral mesh in spherical geometry.